Atmospheric neutrino induced muons in the MACRO detector

A measurement of the flux of neutrino-induced muons using the MACRO detector is presented. Different event topologies, corresponding to different neutrino parent energies can be detected. The upward throughgoing muon sample is the larger event sample. The observed upward-throughgoing muons are 26% fewer than expected and the zenith angle distribution does not fit with the expected one. Assuming neutrino oscillations, both measurements suggest maximum mixing and Dm2 of a few times 10-3 eV2. The other samples are due to the internally produced events and to upward-going stopping muons. These data show a regular deficit of observed events in each angular bin, as expected assuming neutrino oscillations with maximum mixing, in agreement with the analysis of the upward-throughgoing muon sample.Comment: 7 pages 6 figures to appear in the proceedings of XVIII International Conference on Neutrino Physics and Astrophysics (Neutrino'98), Takayama, Japan 4-9 June, 199

Observation of the Shadowing of Cosmic Rays by the Moon using a Deep Underground Detector

Using data collected by the MACRO experiment during the years 1989-1996, we show evidence for the shadow of the moon in the underground cosmic ray flux with a significance of 3.6 sigma. This detection of the shadowing effect is the first by an underground detector. A maximum-likelihood analysis is used to determine that the angular resolution of the apparatus is 0.9+/-0.3 degrees. These results demonstrate MACRO's capabilities as a muon telescope by confirming its absolute pointing ability and quantifying its angular resolution.Comment: 14 pages, 8 figures Submitted to Phys. Rev.

Limits on dark matter WIMPs using upward-going muons in the MACRO detector

We perform an indirect search for Weakly Interacting Massive Particles (WIMPs) using the MACRO detector to look for neutrino-induced upward-going muons resulting from the annihilation of WIMPs trapped in the Sun and Earth. The search is conducted in various angular cones centered on the Sun and Earth to accommodate a range of WIMP masses. No significant excess over the background from atmospheric neutrinos is seen and limits are placed on the upward-going muon fluxes from Sun and Earth. These limits are used to constrain neutralino particle parameters from supersymmetric theory, including those suggested by recent results from DAMA/NaI.Comment: 14 pages, 7 figures, submitted to Phys. Rev.

High energy cosmic ray physics with underground muons in MACRO. I. Analysis methods and experimental results

In this paper, the first of a two-part work, we present the reconstruction and measurement of muon events detected underground by the MACRO experiment at Gran Sasso (E у 1.3 TeV in atmosphere͒. The main aim of this work is to discuss the muon multiplicity distribution as measured in the detector. The data sample analyzed consists of 4.4ϫ10 6 muon events, of which ϳ 263 000 are multiple muons, corresponding to a total live time of 5850 h. In this sample, the observed multiplicities extend above N ϭ35, with intermuon separations up to 50 m and beyond. Additional complementing measurements, such as the inclusive muon flux, the angular distribution, and the muon separation distribution ͑decoherence͒, are also included. The physical interpretation of the results presented here is reported in the following companion paper. ͓S0556-2821͑97͒00615-2͔ PACS number͑s͒: 13.85. Tp, 96.40.De, 96.40.Tv, 98.70.S